In recent years, the popularity of digital cameras has increased rapidly. The main factor in this phenomenon may be attributed to the processing of a photographed image as digital data, permitting the easy storage, management, and erasure by the digital camera of the photographed image, unlike a conventional film camera.
When an image photographed by such a digital camera is to be printed and used as a photograph, it is a common practice to temporarily load the photographed digital image data to a PC (computer) by some means, and output the loaded digital image data to a printing apparatus connected to the PC and print it by using an application running on the PC. Note that as a means for loading the image from the digital camera to the PC, one of the following forms is in the mainstream: a form of connecting the digital camera and the PC via a USB interface cable to communicate with each other; and a form of extracting a memory card (a storage medium in which the sensed digital image data is stored) from the digital camera, and setting the memory card to a card reader of the PC to read the digital image data.
Recently, a so-called photo-direct (PD) technique has been developed, such as a technique (e.g., Japanese Patent Laid-Open No. 2005-33468) in which a digital camera is directly connected to a printing apparatus without the mediacy of a PC to directly transmit digital image data from the digital camera to the printing apparatus, and to print, and a technique in which a memory card reader slot is formed in the printing apparatus to set a memory card, which has been extracted from the digital camera, and to print.
More specifically, in order to directly transmit the image data from the digital camera to the printing apparatus to print, the camera generally transmits image data containing not only a JPEG image but also photographing information, such as a photographing date and photographing condition. This allows the printing apparatus to appropriately perform an image process based on the photographing information, and print. Note that an Exif format or the like is defined as a file format in which a JPEG image file contains such photographing information.
Note that JPEG which is an image compression technique used in the digital camera is one of lossy encoding techniques. In JPEG, the compression ratio can be increased by removing components which are hardly visually recognized from pieces of information in the image data (called raw image data) sensed by the image sensing device.
Some users perform advanced image editing on the PCs to obtain high value-added images. Such users strongly want to edit the raw image data instead of the JPEG image data. To meet this demand, recently, a digital camera has been available on the market, which can be set to a mode wherein raw and JPEG image data are stored as one file in storing the photographed image data as a file in the memory card.
However, the raw image data contains the information of the image data sensed by the image sensing device, and has a large information amount. Consequently, the image file containing both the raw and JPEG image data has a larger information amount. This poses a problem that some printing apparatuses cannot handle such large image data files because of an internal memory capacity limitation.
Also, a printing apparatus has been developed which can achieve high-quality printing in a format in which image data contains raw image data and photographing information. However, it is redundant to transfer a file containing raw and JPEG image data to such printing apparatus.